The invention relates to an apparatus for storing and isolating parts that can be accepted as bulk material.
In particular, the device may accommodate cubical or cylindrical electronic components as the bulk material.
For the automatic equipping of circuit boards or ceramic substrates with SMD components, such as resistors, capacitors, diodes, transistors and the like, automatic placement machines are used that operate, for example, according to what is called pick-and-place design. The supplying of the components is thereby determined by their state when delivered. Thus, for example, corresponding supply modules are provided for bulk material, for magazines, and for belts. A placement head, flange-mounted on a freely programmable positioning unit, moves over these supply modules and over the circuit board centered in stationary fashion in the placement region, or over a ceramic substrate centered in stationary fashion in the placement region. The placement head accepts the components at the removal positions of the supply modules with the aid of a suction pipette, whereupon the respectively accepted component rotates into the assembly position, and is set into the provided placement position on the circuit board or on the ceramic substrate. Subsequently, the substrates equipped in this way are sent on for reflow soldering, whereby the surface mounting of the components is terminated, in particular by means of vapor-phase soldering.
For provision of the components as bulk material, which is particularly economical, apparatuses are used that comprise a supply reservoir for accepting or receiving the bulk material and an orientation canal connected to an exit of the supply reservoir. The cross-section of the orientation canal corresponds to the cross-section of the components, but which is slightly oversized. The entry cross-section of the orientation canal is thus matched to the shape and size of the components in such a way that the components can enter only in the correct position, and only one after the other, and be transported to a removal position. The transport of the components to the removal position can be carried out for example by means of the construction of the transport path as a gravity conveyor, a vibration conveyor or a blown-air conveyor. In the entry region of the orientation canal, a jam of improperly positioned components can occur that can be initiated by a single component blocking the entry cross-section of the orientation canal. The jam can however also be triggered by a bridge formation of two or more parts that become jammed between the walls in the exit region of the supply reservoir.
European Patent Document No. EP-B-0 216 203 discloses that it is known to resolve a jam in the entry region of the orientation canal in an apparatus of the type named above by introducing a gas, so that correctly positioned parts can move up and can enter into the orientation canal.
German Patent Document Nos. DE-C-39 42 996 and DE-A-37 17 918, both disclose that, it is known to shape the entry region of the orientation canal with a cross-section that, beyond its planar floor surface, is limited by a wall surface that runs neither parallel to the floor surface nor at a right angle thereto. By means of this cross-sectional shape, contact between flat surfaces of the components with the wall surfaces, and thus also bridge formations of the components, are supposed to be avoided.
In the known apparatuses for storing and isolating parts that can be accepted as bulk material, the isolation of the components by means of correctly positioned entry into the orientation canal rests on chance. However, this typically results in undesirably long durations for components to pass the region between the orientation canal entry position and the component removal position. On the other hand, the introduction of a gas for the removal of jams or bridge formations can cause damage to the components, due to the high gas pressure required in the turbulence chamber.